Obesity, hypertension, central fat, and non-insulin dependent diabetes mellitus (NIDDM) are more common among black than white women in the U.S. Reasons for this are unknown. One aim of this research is to test the hypothesis that the greater frequency of these phenotypes among black women is, in part, genetically induced. Obesity is a "risk factor" for hypertension, NIDDM, and hyperlipidemia. Whether obesity causally contributes to these conditions among black women is less clear. An alternative explanation must be ruled out. Specifically, the association between obesity and other cardiovascular disease (CVD) risk factors may solely result from each variable being produced by the same genetic factors. The second aim of this research is to test, among black women, the hypothesis that the association between obesity and other CVD risk factors is not solely a function of joint genetic factors. Subjects will be 125 black twin pairs (250 individuals). Body fat will be determined by body composition analyses; Glucose tolerance via two-hour oral glucose tolerance test; Blood pressure via a "random-zero" sphygmomanometer; and Serum lipids by chemical assays. To test Hypothesis 1, an index of racial admixture will be computed for each person, based on genetic markers known to occur with differential frequencies across races. If admixture is correlated with the CVD risk factors, the genetic aspect of race is presumably influential in CVD risk. To test Hypothesis 2, a multivariate genetic analysis will be conducted through structural equation modeling. Such an analysis allows one to determine if obesity is related to CVD risk factors independent of genotype. Black women are chosen for study because of their high rate of CVD and CVD risk factors and because they have been sorely neglected in this research area to date. This research has significance for public health initiatives and CVD prevention among black women. Finally, this is a first step toward a long-term goal of developing an ethnically heterogeneous twin registry for obesity related genetic research.